Pfizer has signed an agreement with Medivation, a San Francisco biopharmaceutical firm focused on small molecules, to codevelop and comarket dimebon, a drug for the treatment of Alzheimer's and Huntington's diseases. Under the agreement, Medivation will receive an up-front payment of $225 million, will be eligible to receive payments of up to $500 million upon the attainment of development and regulatory milestones, and could reap undisclosed commercial milestone payments. Dimebon is currently in Phase III clinical trials for Alzheimer's disease.